Choose the correct answer from the given four options:
The $ 4^{\text {th }} $ term from the end of the AP: $ -11,-8,-5, \ldots, 49 $ is
(A) 37
(B) 40
(C) 43
(D) 58

AcademicMathematicsNCERTClass 10

Given:

Given A.P. is \( -11,-8,-5, \ldots, 49 \).

To do:

We have to find the 4th term from the end of the given arithmetic progression. 

Solution:

In the given A.P.,

$a_1=-11, a_2=-8, a_3=-5$

First term $a_1 = a= -11$, last term $l = 49$

Common difference $d = a_2-a_1 = -8 - (-11) = -8+11=3$

We know that,

nth term from the end is given by $l - (n - 1 ) d$.

Therefore,

4th term from the end $= 49 - (4 - 1) \times (3)$

$= 49 - 3 \times 3$

$= 49 -9$

$= 40$.

The 4th term from the end of the given A.P. is $40$.   

raja
Updated on 10-Oct-2022 13:27:27

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